Thirteen Russian nationals and three Russian entities have been indicted by a federal grand jury, accused of interfering with U.S. elections and political processes, the Justice Department announced Friday.

Update Feb 16, 2018 6:25 PM EST: Facebook issued a statement Friday after the announcement by special prosecutor Robert Mueller's office on the indictments against 13 Russians and three Russian companies for interfering in the 2016 presidential election. "We know we have to do more to prevent future attacks. We're making significant investments, including increasing the number of people working on security from 10,000 to 20,000," Facebook Global Policy Vice President Joel Kaplan said in the statement. Federal authorities said the Russians manipulated social media to interfere in the 2016 election.

New: Statement from Facebook Global Policy VP Joel Kaplan on today’s Russia indictment: "We know we have more to do to prevent against future attacks. We’re making significant investments…" pic.twitter.com/NrzmipBTR8

Update Feb 16, 2018 4:36 PM EST: President Donald Trump said in a tweet Friday that the indictment of 13 Russians and three Russian companies for interfering in the 2016 presidential election proves there was no collusion between his campaign and the Russians. But special counsel Robert Mueller is not finished with his investigation and is still investigating possible collusion between the Trump campaign and Russia, according to Bloomberg, which reported Friday that the Russian indictments represent only part of a larger investigation that is still looking into whether the Trump campaign colluded with the Russians.

Update Feb 16, 2018 3:33 PM EST: President Donald Trump urged unity among Americans in the wake of a federal grand jury indictment Friday that accused 13 Russians and three Russian companies of meddling in U.S. political processes.

"We cannot allow those seeking to sow confusion, discord and rancor to be successful," he said in a statement released by press secretary Sarah Huckabee Sanders on Friday afternoon. "It's time we stop the outlandish partisan attacks, wild and false allegations and far-fetched theories, which only serve to further the agendas of bad actors, like Russia, and do nothing to protect the principles of our institutions."

Sanders highlighted in her statement that "there was NO COLLUSION between the Trump campaign and Russia."

Update Feb 16, 2018 3:19 PM EST: President Donald Trump on Friday highlighted the fact that efforts by Russians to influence America's political process, as detailed by federal prosecutors, started in 2014, "long before I announced that I would run for president."

"The results of the election were not impacted," Trump wrote, echoing statements made earlier Friday by Deputy U.S. Attorney General Rod Rosenstein.

The Justice Department is investigating Russian meddling in the 2016 presidential election and possible ties between those efforts and people who worked on Trump's 2016 presidential campaign.

"The Trump campaign did nothing wrong -- no collusion!" he added.

Russia started their anti-US campaign in 2014, long before I announced that I would run for President. The results of the election were not impacted. The Trump campaign did nothing wrong - no collusion!

Original report: In a 37-page indictment handed down by special prosecutor Robert Mueller's office, officials charged the defendants with conspiracy to defraud the United States. Three of the defendants also face charges of conspiracy to commit wire fraud and bank fraud while five of them were charged with aggravated identity theft.

Prosecutors said the Russian Internet Research Agency employed hundreds of people starting in about 2014 to undermine America’s political processes with the goal of waging "information warfare against the United States of America." The group continued its operations through the 2016 presidential elections, according to the indictment.

The defendants were accused of crafting social media pages and groups and organizing rallies while posing as American political activists. They posted on sites including YouTube, Facebook, Instagram and Twitter. To bolster their identities and mask their links to Russia, they used stolen identity information, according to the indictment.

They posted negative comments about multiple candidates during the 2016 presidential election, but had tailored their efforts by early- to mid-2016 in support of Republican Donald Trump and in opposition of his Democratic opponent, Hillary Clinton, the indictment said.

"There is no allegation in this indictment that any American was a knowing participant in this illegal activity," Deputy U.S. Attorney General Rod Rosenstein said at a news conference Friday. "There is no allegation in the indictment that the (Russians') conduct altered the outcome of the 2016 election."

Deputy AG Rosenstein says indictment charges 13 Russian nationals and 3 Russian companies that were seeking to interfere in the 2016 presidential election. The defendants allegedly conducted, what they called, information warfare against the United States https://t.co/QAN7VQLBDUpic.twitter.com/qxSzLsSSDW

The charges are the most direct allegation to date of illegal Russian meddling in the election. Russian businessman Yevgeniy Viktorovich Prigozhin and the companies he controlled “spent significant funds” to influence American politics, according to the indictment. In a statement obtained by CNN, he called Americans "very impressionable people." "They see what they want to see," he wrote. "I have great respect for them. I'm not at all upset that I'm on this list. If they want to see the devil -- let them see one."

Yevgeniy Prigozhin, Russian businessman who was indicted today, said: “Americans are very impressionable people, they see what they want to see. I have great respect for them. I'm not at all upset that I’m on this list. If they want to see the devil - let them see one."